We did this to our Oracle servers and what a complete pain. We did it to keep all of those processes from sucking down server memory. Well, every installation requires a nice handful of X11 libraries in order to kick off the installer. Yes, starting an application to a remote display still requires a large collection of relevant libraries be available. Our stripped down version was so stripped that getting an application installer to start is a royal pain. All it accomplished was making my DBA mad at me.
My advice is this: let Redhat install all of the X11 apps, libraries, even Gnome if you want. Then just shut them down. Disable them with
xdm as it is sometimes called. You may need to shut down the font server as well (
xfs I think). The installers will be able to find all of their happy libraries to display to a remote box. Addtionally, if you ever need to run the tools from the console, you can just
service start gdm and go from there. When you're done, log out and shut the
gdm service off.
That said, don't let it install a bunch of stupid stuff like Evolution, Empathy, calculators, etc. You may even elect to ditch Gnome and only put on a lightweight window manager. This simplifies what you have to install. Using the Server version will keep these and other things like
bluez (Bluetooth) to a minimum, but you should look through your kickstart to see what else you can safely remove.
One last thing. The best tool for testing an X11 connection is
xdpyinfo as it a) doesn't provide a stupid popup and b) you could script it into regular commands that require a valid X11 connection before allowing the script to continue.